Hybrid vehicles may be used as emergency vehicles such as police interceptors or fire department command and control vehicles. While performing these duties, the vehicles may spend large amounts of time in a stationary state while police officers or firemen perform paperwork or receive information from a dispatch service or other police officers or firemen. The vehicle's engine may be stopped while the vehicle is stopped to conserve chemical fuel (e.g., gasoline). The vehicle's energy storage device may supply electrical energy to electrical consumers such as radios, computer systems, lights, sirens, etc. Such operating conditions may be referred to as electric idle. However, if an amount of charge stored in the energy storage device is reduced to less than a threshold, the vehicle's engine may be started so that an alternator or generator may continue supplying energy to the electrical consumers and recharge the energy storage device. Nevertheless, restarting the engine may not be desirable during some conditions.
The inventors herein have recognized the above-mentioned disadvantages and have developed a method for operating a vehicle, comprising: estimating whether or not a future vehicle electric idle will exceed a threshold energy consumption amount; adjusting a value of an electric energy storage device state of charge (SOC) desired value responsive to an estimate that the future vehicle electric idle will exceed the threshold energy consumption amount; and adjusting an electric energy storage device SOC to the electric energy storage device SOC desired value via the controller.
By estimating whether or not a future vehicle electric idle will exceed a threshold energy consumption amount and adjusting a value of a battery target or desired state of charge based on the estimate of exceeding the threshold energy consumption amount, it may be possible to extend an electric idle duration and reduce a number of times a vehicle's engine is restarted while the vehicle is stationary. Alternatively, an estimate of a threshold electric idle time duration may be provided and the electric energy storage device desired value, or alternatively SOC threshold limit not to be exceeded, may be adjusted responsive to the threshold electric idle time duration. In addition, vehicle occupants may be provided a human/machine input that provides a sole function of adjusting battery state of charge to extend or reduce an amount of charge that may be consumed in an electric idle mode so that a duration of electric idle may be extended. Extending the electric idle time may reduce a number of engine starts. Further, engine starting may be inhibited in electric idle mode so that an amount of time the vehicle is used to silently approach a target may be increased.
The present description may provide several advantages. For example, the approach may reduce a number of engine starts during a time a vehicle is stationary and powering electrical devices. Further, the approach may extend an amount of time a vehicle may be used to silently approach a target. Further still, the approach may make operating the vehicle less objectionable to a driver since the engine may be started and stopped less frequently.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.